Model looks bulky with smooth shader, don't want to subdivide further, would a normal map made from a high poly version make it look better?
A normal map will definitely do what you are thinking of, however once you add a texture to your object you will not notice the 'bulkiness' of your object nearly as much. In fact, I would suggest optimizing your model more by removing some vertices, as adding a texture and normal map will make a lot of them unnecessary. One thing to keep in mind is that triangles are not a bad thing in game models, so use that to your advantage when adding or removing vertices.

When adding a normal map, keep in mind that you can add more details such as creases in the skin, skin texture, scales, etc. For the high poly mesh you will bake the normals from I would suggest using a multiresolution modifier instead of a subsurf and sculpting in as many details as you can before baking.